Piezoelectric polymers with high polydispersity

Abstract

A piezoelectric polymer article may be characterized by a Young's modulus of 5 GPa or greater along at least one dimension thereof. The piezoelectric polymer article may include polyvinylidene fluoride, for example, and may have a polydispersity index of at least 2. A piezoelectric coefficient of the polymer article, which may be a thin film or fiber, may be at least 20 pC/N.

What is claimed is: 
     
         1 . A piezoelectric polymer article having a Young's modulus of at least approximately 5 GPa along at least one dimension of the polymer article. 
     
     
         2 . The piezoelectric polymer article of  claim 1 , wherein the Young's modulus of the polymer article is at least approximately 5 GPa along each of a pair of mutually orthogonal in-plane axes of the polymer article. 
     
     
         3 . The piezoelectric polymer article of  claim 1 , wherein the piezoelectric polymer comprises polyvinylidene fluoride. 
     
     
         4 . The piezoelectric polymer article of  claim 1 , wherein the piezoelectric polymer is characterized by a polydispersity index of at least approximately 2. 
     
     
         5 . The piezoelectric polymer article of  claim 1 , wherein the polymer article comprises a thin film. 
     
     
         6 . The piezoelectric polymer article of  claim 1 , wherein the polymer article comprises a thin film having a uniaxial orientation that is characterized by a stretch ratio of at least approximately 400%. 
     
     
         7 . The piezoelectric polymer article of  claim 1 , wherein the polymer article comprises a thin film having a biaxial orientation that is characterized by a stretch ratio along each orientation of at least approximately 400%. 
     
     
         8 . The piezoelectric polymer article of  claim 1 , wherein a piezoelectric coefficient of the polymer article is at least approximately 20 pC/N along at least one dimension of the polymer article. 
     
     
         9 . The piezoelectric polymer article of  claim 1 , wherein the polymer article is characterized by at least approximately 80% transparency at 550 nm and less than approximately 10% bulk haze. 
     
     
         10 . A piezoelectric polymer article having a polydispersity index of at least approximately 2 and a Young's modulus of at least approximately 5 GPa. 
     
     
         11 . The piezoelectric polymer article of  claim 10 , wherein a piezoelectric coefficient of the polymer article is at least approximately 20 pC/N along at least one dimension of the polymer article. 
     
     
         12 . A method comprising:
 applying a tensile stress to a polymer thin film along at least one direction and in an amount effective to induce at least approximately 500% strain in the polymer thin film and form a piezoelectric polymer article, wherein the polymer thin film comprises less than approximately 10 wt. % liquid solvent.   
     
     
         13 . The method of  claim 12 , wherein the polymer thin film comprises a mixture of a high molecular weight polymer and one or more of a low molecular weight polymer and an oligomer. 
     
     
         14 . The method of  claim 12 , wherein the polymer thin film comprises polyvinylidene fluoride. 
     
     
         15 . The method of  claim 12 , wherein a composition of the polymer thin film is characterized by a polydispersity index of at least approximately 2. 
     
     
         16 . The method of  claim 12 , wherein a composition of the polymer thin film is characterized by a bimodal molecular weight distribution. 
     
     
         17 . The method of  claim 12 , further comprising applying an electric field across a thickness dimension of the polymer thin film while applying the tensile stress. 
     
     
         18 . The method of  claim 12 , further comprising applying an electric field of at least approximately 50 V/micrometer across a thickness dimension of the polymer thin film. 
     
     
         19 . The method of  claim 12 , further comprising irradiating the polymer thin film with actinic radiation. 
     
     
         20 . The method of  claim 12 , further comprising irradiating the polymer thin film with actinic radiation within at least one period selected from the group consisting of (a) prior to the stretching, (b) during the stretching, and (c) following the stretching.